Engine temp.

My engine temperature gauge keeps going from cold to half-way and than back down again every 10 minute, it never gets really hot, just half way and than back, wats causing this problem? this is on the stock engine and i am swapping it out in july so no biggie but i would just like to know.

It's the radiator fan.
When the fan is not operating or you are not moving much the car will usually be warmer, or right after you 'step on it' for awhile.
The fan turns on and cools your car down.
If you call that a problem, wait til you do your swap

yeah i would say its the fan too. Since i put the b16 in the rex my heater has been alot hoter since. as for the water temp gauge it stays pretty much the same. gotta remember that a bigger engine makes more heat.